The digestibility of an animal regarding food and components thereof, such as organic matter digestibility, dry matter digestibility, fiber digestibility, energy digestibility, fat digestibility, or protein digestibility, is important for the health and well-being of the animal. These characteristics of the animal can change in response to age and other factors. Beyond selecting macronutrients and amounts thereof, the ability to modulate organic matter digestibility, dry matter digestibility, fiber digestibility, energy digestibility, fat digestibility, or protein digestibility is difficult. In this regard, most attempts to modulate digestibility are directed to overall digestibility and use macronutrients such as citrus pulp, wheat, corn, apple and beets but not specific compounds.
The specific biological compounds which increase or decrease digestibility are difficult to ascertain. In addition, measuring digestibility can be time and labor intensive. To the best knowledge of the inventors, the current literature only describes enhancement of overall digestibility and only uses differences between macronutrients or, with respect to specific compounds, uses omega-3 polyunsaturated fats, medium chain triglycerides, methionine, 2-hydroxy-4-butanoic acid, diacylglycerol, yttrium oxide, chromic oxide, polydextrose, and lengths of cellulose fibers. Furthermore, studies regarding digestibility tend to be focused on improving stool quality and not the actual absorption of nutrients by the animal itself.